Motion Information Storage for Video Coding and Signaling

ABSTRACT

A method is provided for inter-coding video in which encoder and decoder memory requirements associated with storage of motion information related to collocated coding units is reduced. In some embodiments motion information related to only a single or reduced set of collocated coding unit(s) may be stored at the encoder and decoder. In operation, motion information for multiple coding predictors is determined based upon scaling of motion information from motion information from one of the multiple coding predictors. Additionally, in some embodiments, where multiple lists of collocated picture are available for update, only of the multiple available lists may be updated.

CLAIM OF PRIORITY

This Application claims priority under 35 U.S.C. § 119(e) from earlierfiled U.S. Provisional Application Ser. No. 62/656,743, filed Apr. 12,2018, U.S. Provisional Application Ser. No. 62/656,763, filed Apr. 12,2018, U.S. Provisional Application Ser. No. 62/660, 883, filed Apr. 20,2018 and U.S. Provisional Application Ser. No. 62/678,864, filed May 31,2018 the entireties of each of which are hereby incorporated herein byreference.

TECHNICAL FIELD

The present disclosure relates to the field of video coding,particularly coding efficiency increases and reduced memory burdenassociated with control of the number of stored collocated pictures andmemory requirements.

BACKGROUND

The technical improvements in evolving video coding standards illustratethe trend of increasing coding efficiency to enable higher bit-rates,higher resolutions, and better video quality. The Joint VideoExploration Team developed a new video coding scheme referred to as JVETand is developing a newer video coding scheme referred to a VersatileVideo Coding (VVC)—the complete contents of the VVC 7^(th) edition ofdraft 2 of the standard titled Versatile Video Coding (Draft 2) by JVETpublished Oct. 1, 2018 is hereby incorporated herein by reference.Similar to other video coding schemes like HEVC (High Efficiency VideoCoding), both JVET and VVC are block-based hybrid spatial and temporalpredictive coding schemes. However, relative to HEVC, JVET and VVCinclude many modifications to bitstream structure, syntax, constraints,and mapping for the generation of decoded pictures. JVET has beenimplemented in Joint Exploration Model (JEM) encoders and decoders, butVVC is not anticipated to be implemented until early 2020.

Current and anticipated video coding schemes typically require thatmultiple pictures be stored at both the encoder and decoder in order tocode and decode video. However, transmission and storage of suchinformation can be burdensome. Accordingly, what is needed is a systemand method of motion information storage for video coding and signalingthat reduces system burdens.

SUMMARY

A system of one or more computers can be configured to performparticular operations or actions by virtue of having software, firmware,hardware, or a combination of them installed on the system that inoperation causes or cause the system to perform the actions. One or morecomputer programs can be configured to perform particular operations oractions by virtue of including instructions that, when executed by dataprocessing apparatus, cause the apparatus to perform the actions. Onegeneral aspect can comprise one or more of the following steps:determining motion information associated with a collocated picture set;determining motion information associated with a current coding unit;updating said motion information associated with said collocated pictureset with motion information associated with said current coding unit, ifit is determined that said motion information associated with saidcollocated picture set is to be updated with said motion informationassociated with said current coding unit; encoding said current codingunit, wherein said encoded current coding unit includes an indicatoridentifying whether said motion information associated with said currentcoding unit is used to update said motion information associated withsaid collocated picture set. Other embodiments of this aspect includecorresponding computer systems, apparatus, and computer programsrecorded on one or more computer storage devices, each configured toperform the actions of the methods.

Implementations can include one or more of the following features: themethod of inter-coding wherein a plurality of collocated picture setsare available and one of said plurality of collocated picture sets isupdated; the method of inter-coding wherein said indicator is includedin a NAL unit associated with said current coding until; the method ofinter-coding where said indicator is included within a header of saidNAL unit; the method of inter-coding where said indicator is a singlebit; the method of inter-coding further comprising receiving saidencoded current coding unit; determining whether said encoded currentcoding unit includes said indicator; and storing said motion informationassociated with said current coding unit as part of said collocatedpicture set, if said indicator is determined to be present.Implementations of the described techniques may include hardware, amethod or process, or computer software on a computer-accessible medium.

One general aspect can comprise a system of inter-coding comprising:storing in an encoder memory motion information associated with acollocated picture set; storing in said encoder memory motioninformation associated with a current coding unit; updating said encodermemory with motion information associated with said collocated pictureset with motion information associated with said current coding unit, ifit is determined that said motion information associated with saidcollocated picture set is to be updated with said motion informationassociated with said current coding unit; and encoding said currentcoding unit; where said encoded current coding unit includes anindicator identifying whether said motion information associated withsaid current coding unit is used to update said motion informationassociated with said collocated picture set. Other embodiments of thisaspect include corresponding computer systems, apparatus, and computerprograms recorded on one or more computer storage devices, eachconfigured to perform the actions of the methods.

BRIEF DESCRIPTION OF THE DRAWINGS

Further details of the present invention are explained with the help ofthe attached drawings in which:

FIG. 1 depicts division of a frame into a plurality of Coding Tree Units(CTUs).

FIG. 2a -2c depict exemplary partitioning of a CTU into Coding Units(CUs).

FIG. 3 depicts a quadtree plus binary tree (QTBT) representation of FIG.2's CU partitioning.

FIG. 4 depicts a simplified block diagram for CU coding in a JVET or VVCencoder.

FIG. 5 depicts possible intra prediction modes for luma components inJVET of VVC.

FIG. 6 depicts a simplified block diagram for CU coding in a JVET of VVCdecoder.

FIG. 7 depicts a block diagram of a system and method of motioninformation storage for video coding and signaling.

FIG. 8 depicts a block diagram of a system and method of selection of areference picture.

FIG. 9 depicts a block diagram of a system and method for reducingsystem burden associated with motion information.

FIG. 10 depicts a block diagram of a system and method of motioninformation storage for video coding and signaling.

FIG. 11 depicts a table showing a system and method for reducing systemburden associated with motion information.

FIG. 12 depicts an embodiment of a computer system adapted andconfigured to provide for variable template size for template matching.

FIG. 13 depicts an embodiment of video encoder/decoder adapted andconfigured to provide for variable template size for template matching.

DETAILED DESCRIPTION

FIG. 1 depicts division of a frame into a plurality of Coding Tree Units(CTUs) 100. A frame can be an image in a video sequence. A frame caninclude a matrix, or set of matrices, with pixel values representingintensity measures in the image. Thus, a set of these matrices cangenerate a video sequence. Pixel values can be defined to representcolor and brightness in full color video coding, where pixels aredivided into three channels. For example, in a YCbCr color space pixelscan have a luma value, Y, that represents gray level intensity in theimage, and two chrominance values, Cb and Cr, that represent the extentto which color differs from gray to blue and red. In other embodiments,pixel values can be represented with values in different color spaces ormodels. The resolution of the video can determine the number of pixelsin a frame. A higher resolution can mean more pixels and a betterdefinition of the image, but can also lead to higher bandwidth, storage,and transmission requirements.

Frames of a video sequence can be encoded and decoded using JVET. JVETis a video coding scheme being developed by the Joint Video ExplorationTeam. Versions of JVET have been implemented in JEM (Joint ExplorationModel) encoders and decoders. Similar to other video coding schemes likeHEVC (High Efficiency Video Coding), JVET is a block-based hybridspatial and temporal predictive coding scheme. During coding with JVET,a frame is first divided into square blocks called CTUs 100, as shown inFIG. 1. For example, CTUs 100 can be blocks of 128×128 pixels.

FIG. 2a depicts an exemplary partitioning of a CTU 100 into CUs 102.Each CTU 100 in a frame can be partitioned into one or more CUs (CodingUnits) 102. CUs 102 can be used for prediction and transform asdescribed below. Unlike HEVC, in JVET the CUs 102 can be rectangular orsquare and can be coded without further partitioning into predictionunits or transform units. The CUs 102 can be as large as their root CTUs100, or be smaller subdivisions of a root CTU 100 as small as 4×4blocks.

In JVET, a CTU 100 can be partitioned into CUs 102 according to aquadtree plus binary tree (QTBT) scheme in which the CTU 100 can berecursively split into square blocks according to a quadtree, and thosesquare blocks can then be recursively split horizontally or verticallyaccording to binary trees. Parameters can be set to control splittingaccording to the QTBT, such as the CTU size, the minimum sizes for thequadtree and binary tree leaf nodes, the maximum size for the binarytree root node, and the maximum depth for the binary trees. In VVC, aCTU 100 can be portioned into CUs utilizing ternary splitting also.

By way of a non-limiting example, FIG. 2a shows a CTU 100 partitionedinto CUs 102, with solid lines indicating quadtree splitting and dashedlines indicating binary tree splitting. As illustrated, the binarysplitting allows horizontal splitting and vertical splitting to definethe structure of the CTU and its subdivision into CUs. FIGS. 2b & 2 cdepict alternate, non-limiting examples of ternary splitting of a CUwherein subdivisions of the CUs are non-equal.

FIG. 3 depicts a QTBT representation of FIG. 2's partitioning. Aquadtree root node represents the CTU 100, with each child node in thequadtree portion representing one of four square blocks split from aparent square block. The square blocks represented by the quadtree leafnodes can then be divided zero or more times using binary trees, withthe quadtree leaf nodes being root nodes of the binary trees. At eachlevel of the binary tree portion, a block can be divided eithervertically or horizontally. A flag set to “0” indicates that the blockis split horizontally, while a flag set to “1” indicates that the blockis split vertically.

After quadtree splitting and binary tree splitting, the blocksrepresented by the QTBT's leaf nodes represent the final CUs 102 to becoded, such as coding using inter prediction or intra prediction. Forslices or full frames coded with inter prediction, differentpartitioning structures can be used for luma and chroma components. Forexample, for an inter slice a CU 102 can have Coding Blocks (CBs) fordifferent color components, such as such as one luma CB and two chromaCBs. For slices or full frames coded with intra prediction, thepartitioning structure can be the same for luma and chroma components.

FIG. 4 depicts a simplified block diagram for CU coding in a WETencoder. The main stages of video coding include partitioning toidentify CUs 102 as described above, followed by encoding CUs 102 usingprediction at 404 or 406, generation of a residual CU 410 at 408,transformation at 412, quantization at 416, and entropy coding at 420.The encoder and encoding process illustrated in FIG. 4 also includes adecoding process that is described in more detail below.

Given a current CU 102, the encoder can obtain a prediction CU 402either spatially using intra prediction at 404 or temporally using interprediction at 406. The basic idea of prediction coding is to transmit adifferential, or residual, signal between the original signal and aprediction for the original signal. At the receiver side, the originalsignal can be reconstructed by adding the residual and the prediction,as will be described below. Because the differential signal has a lowercorrelation than the original signal, fewer bits are needed for itstransmission.

A slice, such as an entire picture or a portion of a picture, codedentirely with intra-predicted CUs can be an I slice that can be decodedwithout reference to other slices, and as such can be a possible pointwhere decoding can begin. A slice coded with at least someinter-predicted CUs can be a predictive (P) or bi-predictive (B) slicethat can be decoded based on one or more reference pictures. P slicesmay use intra-prediction and inter-prediction with previously codedslices. For example, P slices may be compressed further than theI-slices by the use of inter-prediction, but need the coding of apreviously coded slice to code them. B slices can use data from previousand/or subsequent slices for its coding, using intra-prediction orinter-prediction using an interpolated prediction from two differentframes, thus increasing the accuracy of the motion estimation process.In some cases P slices and B slices can also or alternately be encodedusing intra block copy, in which data from other portions of the sameslice is used.

As will be discussed below, intra prediction or inter prediction can beperformed based on reconstructed CUs 434 from previously coded CUs 102,such as neighboring CUs 102 or CUs 102 in reference pictures.

When a CU 102 is coded spatially with intra prediction at 404, an intraprediction mode can be found that best predicts pixel values of the CU102 based on samples from neighboring CUs 102 in the picture.

When coding a CU's luma component, the encoder can generate a list ofcandidate intra prediction modes. While HEVC had 35 possible intraprediction modes for luma components, in NET there are 67 possible intraprediction modes for luma components and in VVC there are 85 predictionmodes. These include a planar mode that uses a three dimensional planeof values generated from neighboring pixels, a DC mode that uses valuesaveraged from neighboring pixels, the 65 directional modes shown in FIG.5 that use values copied from neighboring pixels along the solid-lineindicated directions and 18 wide-angle prediction modes that can be usedwith non-square blocks.

When generating a list of candidate intra prediction modes for a CU'sluma component, the number of candidate modes on the list can depend onthe CU's size. The candidate list can include: a subset of HEVC's 35modes with the lowest SATD (Sum of Absolute Transform Difference) costs;new directional modes added for JVET that neighbor the candidates foundfrom the HEVC modes; and modes from a set of six most probable modes(MPMs) for the CU 102 that are identified based on intra predictionmodes used for previously coded neighboring blocks as well as a list ofdefault modes.

When coding a CU's chroma components, a list of candidate intraprediction modes can also be generated. The list of candidate modes caninclude modes generated with cross-component linear model projectionfrom luma samples, intra prediction modes found for luma CBs inparticular collocated positions in the chroma block, and chromaprediction modes previously found for neighboring blocks. The encodercan find the candidate modes on the lists with the lowest ratedistortion costs, and use those intra prediction modes when coding theCU's luma and chroma components. Syntax can be coded in the bitstreamthat indicates the intra prediction modes used to code each CU 102.

After the best intra prediction modes for a CU 102 have been selected,the encoder can generate a prediction CU 402 using those modes. When theselected modes are directional modes, a 4-tap filter can be used toimprove the directional accuracy. Columns or rows at the top or leftside of the prediction block can be adjusted with boundary predictionfilters, such as 2-tap or 3-tap filters.

The prediction CU 402 can be smoothed further with a position dependentintra prediction combination (PDPC) process that adjusts a prediction CU402 generated based on filtered samples of neighboring blocks usingunfiltered samples of neighboring blocks, or adaptive reference samplesmoothing using 3-tap or 5-tap low pass filters to process referencesamples.

When a CU 102 is coded temporally with inter prediction at 406, a set ofmotion vectors (MVs) can be found that points to samples in referencepictures that best predict pixel values of the CU 102. Inter predictionexploits temporal redundancy between slices by representing adisplacement of a block of pixels in a slice. The displacement isdetermined according to the value of pixels in previous or followingslices through a process called motion compensation. Motion vectors andassociated reference indices that indicate pixel displacement relativeto a particular reference picture can be provided in the bitstream to adecoder, along with the residual between the original pixels and themotion compensated pixels. The decoder can use the residual and signaledmotion vectors and reference indices to reconstruct a block of pixels ina reconstructed slice.

In JVET, motion vector accuracy can be stored at 1/16 pel, and thedifference between a motion vector and a CU's predicted motion vectorcan be coded with either quarter-pel resolution or integer-pelresolution.

In JVET motion vectors can be found for multiple sub-CUs within a CU102, using techniques such as advanced temporal motion vector prediction(ATMVP), spatial-temporal motion vector prediction (STMVP), affinemotion compensation prediction, pattern matched motion vector derivation(PMMVD), and/or bi-directional optical flow (BIO).

Using ATMVP, the encoder can find a temporal vector for the CU 102 thatpoints to a corresponding block in a reference picture. The temporalvector can be found based on motion vectors and reference pictures foundfor previously coded neighboring CUs 102. Using the reference blockpointed to by a temporal vector for the entire CU 102, a motion vectorcan be found for each sub-CU within the CU 102.

STMVP can find motion vectors for sub-CUs by scaling and averagingmotion vectors found for neighboring blocks previously coded with interprediction, together with a temporal vector.

Affine motion compensation prediction can be used to predict a field ofmotion vectors for each sub-CU in a block, based on two control motionvectors found for the top corners of the block. For example, motionvectors for sub-CUs can be derived based on top corner motion vectorsfound for each 4×4 block within the CU 102.

PMMVD can find an initial motion vector for the current CU 102 usingbilateral matching or template matching. Bilateral matching can look atthe current CU 102 and reference blocks in two different referencepictures along a motion trajectory, while template matching can look atcorresponding blocks in the current CU 102 and a reference pictureidentified by a template. The initial motion vector found for the CU 102can then be refined individually for each sub-CU.

BIO can be used when inter prediction is performed with bi-predictionbased on earlier and later reference pictures, and allows motion vectorsto be found for sub-CUs based on the gradient of the difference betweenthe two reference pictures.

In some situations local illumination compensation (LIC) can be used atthe CU level to find values for a scaling factor parameter and an offsetparameter, based on samples neighboring the current CU 102 andcorresponding samples neighboring a reference block identified by acandidate motion vector. In JVET, the LIC parameters can change and besignaled at the CU level.

For some of the above methods the motion vectors found for each of aCU's sub-CUs can be signaled to decoders at the CU level. For othermethods, such as PMMVD and BIO, motion information is not signaled inthe bitstream to save overhead, and decoders can derive the motionvectors through the same processes.

After the motion vectors for a CU 102 have been found, the encoder cangenerate a prediction CU 402 using those motion vectors. In some cases,when motion vectors have been found for individual sub-CUs, OverlappedBlock Motion Compensation (OBMC) can be used when generating aprediction CU 402 by combining those motion vectors with motion vectorspreviously found for one or more neighboring sub-CUs.

When bi-prediction is used, JVET can use decoder-side motion vectorrefinement (DMVR) to find motion vectors. DMVR allows a motion vector tobe found based on two motion vectors found for bi-prediction using abilateral template matching process. In DMVR, a weighted combination ofprediction CUs 402 generated with each of the two motion vectors can befound, and the two motion vectors can be refined by replacing them withnew motion vectors that best point to the combined prediction CU 402.The two refined motion vectors can be used to generate the finalprediction CU 402.

At 408, once a prediction CU 402 has been found with intra prediction at404 or inter prediction at 406 as described above, the encoder cansubtract the prediction CU 402 from the current CU 102 find a residualCU 410.

The encoder can use one or more transform operations at 412 to convertthe residual CU 410 into transform coefficients 414 that express theresidual CU 410 in a transform domain, such as using a discrete cosineblock transform (DCT-transform) to convert data into the transformdomain. JVET allows more types of transform operations than HEVC,including DCT-II, DST-VII, DST-VII, DCT-VIII, DST-I, and DCT-Voperations. The allowed transform operations can be grouped intosub-sets, and an indication of which sub-sets and which specificoperations in those sub-sets were used can be signaled by the encoder.In some cases, large block-size transforms can be used to zero out highfrequency transform coefficients in CUs 102 larger than a certain size,such that only lower-frequency transform coefficients are maintained forthose CUs 102.

In some cases a mode dependent non-separable secondary transform(MDNSST) can be applied to low frequency transform coefficients 414after a forward core transform. The MDNSST operation can use aHypercube-Givens Transform (HyGT) based on rotation data. When used, anindex value identifying a particular MDNSST operation can be signaled bythe encoder.

At 416, the encoder can quantize the transform coefficients 414 intoquantized transform coefficients 416. The quantization of eachcoefficient may be computed by dividing a value of the coefficient by aquantization step, which is derived from a quantization parameter (QP).In some embodiments, the Qstep is defined as 2^((QP-4)/6). Because highprecision transform coefficients 414 can be converted into quantizedtransform coefficients 416 with a finite number of possible values,quantization can assist with data compression. Thus, quantization of thetransform coefficients may limit an amount of bits generated and sent bythe transformation process. However, while quantization is a lossyoperation, and the loss by quantization cannot be recovered, thequantization process presents a trade-off between quality of thereconstructed sequence and an amount of information needed to representthe sequence. For example, a lower QP value can result in better qualitydecoded video, although a higher amount of data may be required forrepresentation and transmission. In contrast, a high QP value can resultin lower quality reconstructed video sequences but with lower data andbandwidth needs.

NET can utilize variance-based adaptive quantization techniques, whichallows every CU 102 to use a different quantization parameter for itscoding process (instead of using the same frame QP in the coding ofevery CU 102 of the frame). The variance-based adaptive quantizationtechniques adaptively lowers the quantization parameter of certainblocks while increasing it in others. To select a specific QP for a CU102, the CU's variance is computed. In brief, if a CU's variance ishigher than the average variance of the frame, a higher QP than theframe's QP may be set for the CU 102. If the CU 102 presents a lowervariance than the average variance of the frame, a lower QP may beassigned.

At 420, the encoder can find final compression bits 422 by entropycoding the quantized transform coefficients 418. Entropy coding aims toremove statistical redundancies of the information to be transmitted. InNET, CABAC (Context Adaptive Binary Arithmetic Coding) can be used tocode the quantized transform coefficients 418, which uses probabilitymeasures to remove the statistical redundancies. For CUs 102 withnon-zero quantized transform coefficients 418, the quantized transformcoefficients 418 can be converted into binary. Each bit (“bin”) of thebinary representation can then be encoded using a context model. A CU102 can be broken up into three regions, each with its own set ofcontext models to use for pixels within that region.

Multiple scan passes can be performed to encode the bins. During passesto encode the first three bins (bin0, bin1, and bin2), an index valuethat indicates which context model to use for the bin can be found byfinding the sum of that bin position in up to five previously codedneighboring quantized transform coefficients 418 identified by atemplate.

A context model can be based on probabilities of a bin's value being ‘0’or ‘1’. As values are coded, the probabilities in the context model canbe updated based on the actual number of ‘0’ and ‘1’ values encountered.While HEVC used fixed tables to re-initialize context models for eachnew picture, in NET the probabilities of context models for newinter-predicted pictures can be initialized based on context modelsdeveloped for previously coded inter-predicted pictures.

The encoder can produce a bitstream that contains entropy encoded bits422 of residual CUs 410, prediction information such as selected intraprediction modes or motion vectors, indicators of how the CUs 102 werepartitioned from a CTU 100 according to the QTBT structure, and/or otherinformation about the encoded video. The bitstream can be decoded by adecoder as discussed below.

In addition to using the quantized transform coefficients 418 to findthe final compression bits 422, the encoder can also use the quantizedtransform coefficients 418 to generate reconstructed CUs 434 byfollowing the same decoding process that a decoder would use to generatereconstructed CUs 434. Thus, once the transformation coefficients havebeen computed and quantized by the encoder, the quantized transformcoefficients 418 may be transmitted to the decoding loop in the encoder.After quantization of a CU's transform coefficients, a decoding loopallows the encoder to generate a reconstructed CU 434 identical to theone the decoder generates in the decoding process. Accordingly, theencoder can use the same reconstructed CUs 434 that a decoder would usefor neighboring CUs 102 or reference pictures when performing intraprediction or inter prediction for a new CU 102. Reconstructed CUs 102,reconstructed slices, or full reconstructed frames may serve asreferences for further prediction stages.

At the encoder's decoding loop (and see below, for the same operationsin the decoder) to obtain pixel values for the reconstructed image, adequantization process may be performed. To dequantize a frame, forexample, a quantized value for each pixel of a frame is multiplied bythe quantization step, e.g., (Qstep) described above, to obtainreconstructed dequantized transform coefficients 426. For example, inthe decoding process shown in FIG. 4 in the encoder, the quantizedtransform coefficients 418 of a residual CU 410 can be dequantized at424 to find dequantized transform coefficients 426. If an MDNSSToperation was performed during encoding, that operation can be reversedafter dequantization.

At 428, the dequantized transform coefficients 426 can be inversetransformed to find a reconstructed residual CU 430, such as by applyinga DCT to the values to obtain the reconstructed image. At 432 thereconstructed residual CU 430 can be added to a corresponding predictionCU 402 found with intra prediction at 404 or inter prediction at 406, inorder to find a reconstructed CU 434.

At 436, one or more filters can be applied to the reconstructed dataduring the decoding process (in the encoder or, as described below, inthe decoder), at either a picture level or CU level. For example, theencoder can apply a deblocking filter, a sample adaptive offset (SAO)filter, and/or an adaptive loop filter (ALF). The encoder's decodingprocess may implement filters to estimate and transmit to a decoder theoptimal filter parameters that can address potential artifacts in thereconstructed image. Such improvements increase the objective andsubjective quality of the reconstructed video. In deblocking filtering,pixels near a sub-CU boundary may be modified, whereas in SAO, pixels ina CTU 100 may be modified using either an edge offset or band offsetclassification. JVET's ALF can use filters with circularly symmetricshapes for each 2×2 block. An indication of the size and identity of thefilter used for each 2×2 block can be signaled.

If reconstructed pictures are reference pictures, they can be stored ina reference buffer 438 for inter prediction of future CUs 102 at 406.

During the above steps, JVET allows a content adaptive clippingoperations to be used to adjust color values to fit between lower andupper clipping bounds. The clipping bounds can change for each slice,and parameters identifying the bounds can be signaled in the bitstream.

FIG. 6 depicts a simplified block diagram for CU coding in a JVETdecoder. A JVET decoder can receive a bitstream containing informationabout encoded CUs 102. The bitstream can indicate how CUs 102 of apicture were partitioned from a CTU 100 according to a QTBT structure,prediction information for the CUs 102 such as intra prediction modes ormotion vectors, and bits 602 representing entropy encoded residual CUs.

At 604 the decoder can decode the entropy encoded bits 602 using theCABAC context models signaled in the bitstream by the encoder. Thedecoder can use parameters signaled by the encoder to update the contextmodels' probabilities in the same way they were updated during encoding.

After reversing the entropy encoding at 604 to find quantized transformcoefficients 606, the decoder can dequantize them at 608 to finddequantized transform coefficients 610. If an MDNSST operation wasperformed during encoding, that operation can be reversed by the decoderafter dequantization.

At 612, the dequantized transform coefficients 610 can be inversetransformed to find a reconstructed residual CU 614. At 616, thereconstructed residual CU 614 can be added to a corresponding predictionCU 626 found with intra prediction at 622 or inter prediction at 624, inorder to find a reconstructed CU 618.

At 620, one or more filters can be applied to the reconstructed data, ateither a picture level or CU level. For example, the decoder can apply adeblocking filter, a sample adaptive offset (SAO) filter, and/or anadaptive loop filter (ALF). As described above, the in-loop filterslocated in the decoding loop of the encoder may be used to estimateoptimal filter parameters to increase the objective and subjectivequality of a frame. These parameters are transmitted to the decoder tofilter the reconstructed frame at 620 to match the filteredreconstructed frame in the encoder.

After reconstructed pictures have been generated by findingreconstructed CUs 618 and applying signaled filters, the decoder canoutput the reconstructed pictures as output video 628. If reconstructedpictures are to be used as reference pictures, they can be stored in areference buffer 630 for inter prediction of future CUs 102 at 624.

Motion information of a current picture is said to have strongcorrelation with motion information of the previously coded picture(s).Motion information of a block can include the block's coding mode,motion vectors and reference indices from reference lists. A currentblock in a current picture can use motion information of its collocatedblock in previously coded pictures to derive its own motion information.This concept has been used in the existing video compression standards,such as MPEG-4 AVC/H.264, HEVC, VP 9, VP 10 and other compressionmethods. In fact, MPEG-4 AVC/H.264, HEVC and VVC derives their directmode for a current block in a current picture using the motioninformation of the current block's collocated block in one of thepreviously coded pictures. Additionally, HEVC and VVC derive bothtemporal motion vector prediction (TMVP) and merge mode for a currentblock in a current picture using motion information of the currentblock's collocated block in one of the previously coded pictures.

Temporal predication with multiple reference pictures is one of thepowerful tools in many existing video compression standards, such as, byway of non-limiting example MPEG-4 AVC/H.264, HEVC and VVC. Inoperation, for a current (inter) picture, among the reference pictures,one of the reference pictures is defined as collocated picture andmotion information of all the blocks of the collocated picture will beavailable for coding/decoding blocks of the current picture. The motioninformation, including mode, motion vectors and reference indices fromthe reference lists, of all blocks in the collocated pictures thereforeneed to be kept/stored at/in both encoder and decoder. In addition,since a current picture can use any reference picture in a referencepicture buffer as its collocated picture, the motion information of allthe reference pictures is stored. This storage is very costly in termsof encoder and decoder memories.

In operation in HEVC, one enabled flag at the SPS,sps_temporal_mvp_enabled_flag, is defined to enable/disable using oftemporal motion information for a whole sequence. Once it is enabled atthe SPS level, another enabled flag, slice_temporal_mvp_enabled_flag, issignalled at the slice level to further control whether temporal motioninformation is to be used or not for the current slice. If temporalmotion information is enabled at the slice level, one syntax element,collocated_from_10_flag, is then defined in the slice header. This flagis used to indicate which list is to be used to identify the collocatedpicture. If collocated_from_10_flag is equal to 1, it specifies that thecollocated picture is to be defined from list 0, otherwise, ifcollocated_from_10_flag is equal to 0, the collocated picture is to bedefined from list 1. If the number of reference pictures in theidentified list is only one, the picture in the identified list will beconsidered as the collocated picture, otherwise, if the number ofreference pictures in the identified list is more than one, anothersyntax element, collocated_ref_idx, is used to identify which picture inthe identified list is to be identified as the collocated picture. Byway of non-limiting example, if collocated_from 10_flag is 1, there arefive reference pictures are defined in list 0, and collocated_ref_idx is2, the third picture in list 0 would be identified as the collocatedpicture.

Because any picture in the reference picture set (RPS) can be employedas a collocated picture and it is an encoder choice to select whichpicture in the RPS is set as the collocated picture, motion informationfor all reference pictures must be kept/stored at both encoder anddecoder. In the HEVC system, motion information is kept based upon blocksizes of 16×16 to have a better trade-off between coding performance andmemory consumption requirement(s). Thus, in a situation in which fivereference pictures are defined for coding a 1080p sequence in one HEVEencoder/decoder, 8160 blocks of size 16×16 ((1920/16)* (1080/16)) forone picture will be required. For B picture, there will be list 0 andlist 1. 16 bits are required to store a motion vector and there arehorizontal and vertical components for each motion vector. As a result,there are 5*8160*2*2*2=326,400 bytes needed to store all required motionvectors. For each block, the coding mode and reference index for bothlists also need to be stored. Thus, in a system in which one byte isneeded to store the mode and another two bytes are required for possibletwo reference indexes, another 5*8160*3=122,400 bytes are needed tostore all information. Furthermore, additional memory is also needed tostore the reference picture set (RPS) for all slices of allcoded/decoded reference pictures. Thus, at least 448,800 bytes areneeded to store temporal motion information in such a limited example.

In the JVET system, a smaller block size of 4×4 has been proposed toprovide fine motion information. Therefore, the memory consumptionrequirement for JVET could be sixteen times more compared with that forHEVC.

FIG. 7 depicts an efficient method of motion information storage forvideo coding and signaling. 700. In the embodiment depicted in FIG. 7,in step 702 motion information associated with a collocated picture isdetermined, then in step 704 motion information associated with acurrent picture and encoding current picture is determined. In step 706,the motion information for each of the collocated picture and thecurrent picture are compared and in step 708 it is determined whethermotion information associated with the current picture or the collocatedpicture should be updated and transmitted. In some embodiments, step 706may be absent. If, in step 708, it is determined that motion informationshould not be updated, then in step 710, the system can proceed toencode the picture and include a flag indicator in the packet thatindicates that the most recently stored motion information should beused for decoding the picture. However, if in step 708 it is determinedthat motion information should be updated, then in step 712 the motioninformation can be extracted for coding, in step 714 motion informationstored at the encoder can be updated and then in step 716 an indicatorcan be established for inclusion in the encoded transmission that cansignal to the decoder that the collocated motion information should beupdated. Then in step 710, the updated collocation motion information,and indicator can be encoded with the picture in step 710. As depicted,in FIG. 7, in some embodiments, step 712 can provide informationdirectly to the encoding step 710 and/or to step 714. Additionally, insome embodiments, step 712 and/or step 708 can directly trigger the stepof setting the update indicator in step 716. That is, in someembodiments steps 714 and 716 may occur in parallel or in a sequenceother than sequentially, as depicted in FIG. 7.

In step 718, a picture encoded in step 710 can be transmitted andreceived. In step 720 the recipient decoder can decode the receivedpicture and determine whether the received transmission includes anindicator to update or replace its collocated motion information. If thetransmission does not contain an indicator indicating thatupdate/replacement of the collocated motion information is instructed,then the decoder can proceed to step 718 and await/receive the nextpicture. However, it is step 720 the decoder detects that an indicatorhas been received to update the collocated motion information, then areplacement/update decision can be triggered in step 722 and in step 724the updated collocated motion information can be extracted and in step726 the collocated motion information stored at the decoder can beupdated in step 726, before the system proceeds back to step 718 toawait/receive the next picture. However, in some alternate embodiments,the decoding 722 can proceed in parallel with the step 724 and 726and/or decoding 722 can receive updated collocated motion informationdirectly from step 724.

As described in relation to FIG. 7, in operation for a current picture,only the motion information of its collocated picture need bekept/stored at both encoder and decoder, and the motion information ofother reference pictures in the reference buffer need not be kept/storedat the encoder and decoder. As described in reference to FIG. 7, inoperation since there is only one collocated picture per currentpicture, the memory requirement for storing the motion information atboth the encode and decoder can be reduced by N (=N/1) times, assumingthere were N reference pictures in the reference buffer utilizingprevious systems, as compared with the existing video coding standards.

Thus, in operation, the encoder can, using any known, convenient and/ordesired system and/or method, determine if a current coded slice/picturewill be used as collocated picture for the future pictures. If yes, thecurrent coded picture will be signaled and its motion information,including its blocks' modes, motion vectors and reference indices fromthe reference lists, will be kept/stored for future coding/decoding, andthe previously stored motion information of the past collocated picturewill be replaced by the motion information of the new collocatedpicture. In some alternate embodiments, more than one referencepicture/slice can be stored.

Moreover, depending on different applications, for a current block in acurrent picture, its collocated block in the collocated picture can bedefined differently. By way of non-limiting example, the collocatedblock can be defined as the bottom right or center block related to theposition of current block in the collocated picture, as in HEVC.However, in some alternate embodiments, a collocated block can bedefined as a block pointed by motion vector and reference index of oneof inter spatial neighboring block of current block, as in JVET and/orVVC.

Additionally, in some embodiments, motion information of a collocatedblock can serve as motion information of one of the candidates of mergemode or as a motion vector predictor for coding a current block in thecurrent picture and, in some embodiments, a collocated picture may notbe a reference picture, but can be a non-reference picture.

At the decode side, the signaled flag can be decoded to check if thecurrent decoded slice/picture is to be used as collocated picture forfuture pictures. If yes, the motion information of the current decodedpicture, including its blocks' modes, motion vectors and referenceindices from the reference lists, are to be kept/stored for futurecoding/decoding, and the previously stored motion information of thepast collocated picture can be be replaced by the motion information ofthe new collocated picture. Thus, in some embodiments, a collocatedpicture may not necessarily be a reference picture for a current pictureand it can be any previously coded/decoded picture.

In current systems, the collocated picture was signaled at SPS and slicelevels. However, earlier signaling can improve performance andefficiency. Accordingly, as depicted in FIG. 7, signaling of thecollocated picture can be indicated at the Network Abstraction Layer(NAL) unit level to provide more flexibility. By way of non-limitingexample, in some embodiments, the NAL type can be changed to indicatewhether the current CVS (coded video sequence) is a collocated pictureor not. In an alternate embodiment, a one-bit flag can be added in theNAL to indicate whether the current CVS (coded video sequence) is acollocated picture or not.

In some embodiments, the video coding unit is a (Network AbstractionLayer) NAL unit or a slice unit having similar definition in VVC, HEVCor JVET, and signaling of a collocated picture can happen at the NAL orslice levels. However, in some embodiments, a single coding picture canhave more than one NAL or slice. Thus, in some embodiments, if one NALunit or slice is signaled to be the collocated picture, other NAL unitsor slices associated with the same picture can be signaled to be thecollocated picture, thereby further reducing bandwidth requirementsassociated with video transmission. That is for a given picture referredto by the collocated picture, the signaling flag should be the same forall slices/NAL unit of a coded picture.

FIG. 8 depicts a block diagram 800 of a system and method of selectionof a reference picture. In the embodiment depicted in FIG. 8, in step802 information regarding a CU is received and then in step 804information regarding a collocated picture is determined. In step 806 itis determined whether the collocated picture is comprised of more thanone slice or NAL. If in step 806 it is determined that the collocatedpicture is comprised of more than one slice or NAL, then in step 808 allslices/NALs associated with the picture are used to identify the pictureas a reference picture and encoding can proceed in step 810. However, ifin step 806 it is determined that the collocated picture is comprised ofonly one slice or NAL, then encoding can proceed in a standard manner instep 810.

In some embodiments as depicted in FIG. 9, in order to further reducememory usage, normalized motion information can be used instead ofcomplete or compressed motion information. Thus, in some embodiments,once a picture is selected as a collocated picture, the motion vector(s)for each of the selected collocated picture's blocks can be normalizedbased upon the POC difference between the picture and the block'scorresponding reference picture and then stored in accordance with thefollowing equations:

MV_x_stored=MV_x/(POC_picture−POC_reference)

MV_y_stored=MV_y/(POC_picture−POC_reference)

wherein, POC_picture and POC_reference denote POC of the picture and POCof reference picture for the block, and MV_x and MV_y denote the (x,y)components of motion vector for the block. The motion vector componentsof MV_x and MV_y can then be normalized as MV_x_stored and MV_y_stored.

The normalized (MV_x_stored, MV_y_stored) motion vector can then bestored for the collocated picture. Depending on the desired application,the block size for motion vector storage can be different. By way ofnon-limiting example, a size of 16×16 and 4×4 can be used for HEVC andWET or VVC, respectively. However, in alternate embodiments any known,convenient and/or desired size can be employed.

At the encoder side, if the current encoding picture is selected as thecollocated picture for other pictures, some or all of the motion vectorsfor some or all of the blocks in the current encoding picture can bestored. Alternately, if, at the decoder side, the current decodingpicture is selected as collocated picture, some or all the motionvectors for some or all the blocks in the current decoding picture willbe stored.

In some embodiments in which more than one list exists, all MVs for alllists can be normalized. Moreover, if the current block is an intrablock, the MV can be set as 0, as follows:

MV_x_stored=0

MV_y_stored=0

It is noteworthy that once a motion vector for a block is normalized,the associated reference index and coding mode need not be stored.

In some embodiments, a motion vector for only one list instead of twolists can be stored to reduce the memory requirements/usage.

By way of non-limiting example, in some embodiments normalized motionvectors can be determined and stored for the collocated pictureaccording to the above-provided equations. Thus, when a current block isencoded in a current picture, the POC for the current picture and thecollocated picture are POC_current and POC_collocated, respectively.Accordingly, the temporal motion vector predictor (MV_x_TMVP, MV_y_TMVP)for the current block can be obtained by scaling the normalized motionvector of its collocated block based upon the POC difference between thecurrent coding picture and its collocated picture in accordance with thefollowing equations:

MV_x_TMVP=MV_x_col_stored*(POC_current−POC_collocated)

MV_y_TMVP=MV_y_col_stored*(POC_current−POC_collocated)  (3)

where (MV_x_col_stored, MV_y_col_stored) are two components of thestored normalized motion vector for the collocated block in thecollocated picture. Thus, in some embodiments, the collocated block canhave different definitions depending on different applications. By wayof non-limiting example, in some embodiments, a collocated block can bedefined as a block in the same position in the collocated picture inHEVC and can then be defined as a block which is pointed by a motionvector and a reference picture of a spatial neighbor of the currentblock.

In the block flow diagram 900 depicted in FIG. 9, in step 902 acollocated picture is selected and then in step 904 collocated pictureblocks are determined. In step 906 a normalized motion vector can bescaled prior to encoding in step 908. Then in step 910 normalizedcollocated picture blocks can be determined as described herein and theencoded signal can be transmitted in step 912. At the decoder side, instep 914 a bitstream can be received in step, then, if normalized MVsare indicated, the normalized MV information can be scaled in step 916in accordance with techniques described herein and the normalized motionvector can be stored for use as a future collocated picture block. Thenin step 920 the signal can be decoded in accordance with techniques andsystems described herein and a picture can be reconstructed in step 922.

In accordance with some embodiments as depicted in FIG. 10, more thanone identified collocated picture can be identified, but not allidentified collocated pictures may be updated. That is, in someembodiments there can be a number of N pictures considered as collocatedpictures where N is an integer and may be larger than one. The Ncollocated pictures can be identified as a collocated picture set (CPS)and CPS can be managed in a similarly to reference picture set (RPS) inHEVC and/or in any other known, convenient and/or desired manner. Insome embodiments, a CPS can contain the POC information for eachcollocated picture and can be formed by using first in first out (FIFO)methodology and/or any other known convenient and/or desiredmethodology. That is, if a new collocated picture is identified, it canbe appended to the current CPS if the number of collocated picturesidentified in the CPS is less than N and/or a newly identifiedcollocated picture can replace the oldest collocated pictures within thelist of N entries, in the case where the CPS currently contains Nentries. In alternate embodiments, a first index can be signaled tospecify the index of collocated picture in CPS to be replaced by a newcollocated picture. Thus, in some embodiments, a special index can becoded to specify which collocated picture in the CPS is used if N islarger than one. The special index can be signaled at the CU, picture,or other level. In some embodiments, all blocks of current picture canuse the same collocated picture. However, in alternate embodiments,blocks of a current picture can use different collocated pictures andwhich collocated picture is to be used can be specified by the specialindex for each block. However, in a special case in which the number ofcollocated pictures is one, there would be no need to have a specialindex coded to specify the collocated picture. Thus in the situationwhere the CPS contains multiple entries, for each coded picture, if thecoded picture is considered as a collocated picture for other futurepictures, the coded picture can be specified and the motion informationof the coded picture, either motion related information or normalizedmotion information, can be kept/stored and this new collocated picturecan be inserted CPS or replace an existing entry in the current CPS.

In some embodiments, for a current picture, a special index can identifywhich collocated picture in the CPS is to be used for the currentpicture. The collocated picture for current picture can then bedetermined according to such a special index. If a current codedslice/picture is to be used as collocated picture for future pictures, aflag indicating usage of the current coded picture as a collocatedpicture for future pictures and possibly an index indicating whichcollocated picture in the CPS is to be removed and replaced by thecurrent picture can be signaled and its motion information, includingits blocks' modes, motion vectors and reference indices from thereference lists or normalized motion information, can be kept/stored forfuture coding/decoding.

At the decode side, for a current picture, an index which specifies thecollocated picture in CPS can be decoded before decoding the current.The collocated picture for the current picture can then be determinedaccording to the identified decoded index. Thus, in some embodiments,the signaled flag can be decoded to verify whether the current decodedslice/picture will be used as collocated picture for future pictures. Ifit is determined that the current decoded slice/picture will be used asa collocated picture for future pictures then the motion information ofthe current decoded picture, including its blocks' modes, motion vectorsand reference indices from the reference lists or normalized motioninformation, can be kept/stored for future coding/decoding, and thepreviously stored motion information of one of collocated pictures (forexample, the first stored past collocated picture) can be replaced bythe motion information of the new collocated picture.

In some embodiments in which blocks of current picture can use adifferent collocated picture, a special index can be coded for eachblock before coding the current block instead of coding a special indexfor a whole picture. By way of non-limiting example, in the case wherethere are two collocated pictures in the CPS, when the current pictureis encode/decode, an index, which can be in the current slice header,can indicate which of the two pictures is to be the collocated picturefor all blocks of the current picture. Thus, there is a choice to selectwhich collocated picture is used for the current picture according tothe encoded/decoded index.

FIG. 10 depicts a block flow diagram of an efficient method of motioninformation storage for video coding and signaling. 1000. In theembodiment depicted in FIG. 10, in step 1002 motion informationassociated with a collocated picture of an encoding current picture isdetermined, then in step 1004 motion information associated with aCollocated Picture Set (CPS) and encoding current picture is determined.In step 1006, an indicator can be established for inclusion in theencoded transmission that can signal to the decoder whether collocatedmotion information in the CPS should be updated, then in step 1008encoding can proceed. Then in step 1010 the motion information for thecurrent picture can be compared against motion information in the CPS.In step 1012 it can be determined whether replacement of motioninformation in the CPS is desired. If in step 1012 it is determined thatupdate of the motion information in the CPS is desired, then in step1014, the collocation motion information can be updated in the CPS andthe system can return to step 1002. In some embodiments the signal canindicate replacement of a specific entry in the CPS. However, inalternate embodiments, as described herein, a FIFO system can be usedfor updates to the CPS and in still further alternate embodiments, theCPS can be updated in any known, convenient and/or desired manner.However, if in step 1012 it is determined that update of the CPS is notdesired, then the system can return to step 1002

In step 1016, a picture encoded in step 1008 can be transmitted andreceived. In step 1018 the recipient decoder can decode that portion ofthe stream related to whether there is an update to the CPS anddetermine whether to update or replace an entry in the CPS in step 1020.If in step 1020 it is determined that no update/replacement in the CPSis required, then decoding can proceed using the current CPS in step1026. However, if in step 1020 it is determined that anupdate/replacement to the CPS is indicated, then in step 1022 the motioninformation can be extracted and the CPS can be updated in step 1024prior to decoding of the balance of the bitstream in step 1026. In somealternate embodiments, the decoding 1018 can proceed in parallel withthe step 1022 and 1024 and/or decoding 1018 can receive updatedcollocated motion information directly from step 1022.

FIG. 11 depicts a tabular view of an alternate system and method toadjust memory requirements for stored temporal motion vectors 1100. Insome embodiments, the resolution of a stored temporal motion vector canbe included in the bitstream. By way of non-limiting example, theresolution of a stored temporal motion vector can be explicitly signaleddirectly in the bitstream. That is, in some embodiments, the resolutionof stored temporal motion vector can be specified and included inbitstream at the SPS, PPS or other levels. Additionally, in someembodiments, a syntax element can be specified to indicate either eighthpel, quarter pel, integer pel, four pel and/or a combination of pelpossibilities and can be used to store motion vectors according todifferent applications or different needs or desires. The resolution canbe selected based on the application, need or desire to implement agiven resolution. In some embodiments, a resolution of the stored motionvector can be selected or designated by a user.

In some embodiments, the size of a stored temporal motion vector can beincluded in the bitstream. By way of non-limiting example, the size of astored temporal motion vector can be specified and included inbitstream, at the SPS, PPS or other levels. Moreover, in someembodiments, a syntax element can be specified to indicate either onebyte, two bytes, or four bytes, or a combination of byte possibilitiescan be used to store each component of motion vector.

As noted above, in some embodiments, in order to further reduce memoryusage, normalized motion information can be used instead of complete orcompressed motion information. Thus, in some embodiments, once a pictureis selected as a collocated picture, the motion vector(s) for each ofthe selected collocated picture's blocks can be normalized based uponthe POC difference between the picture and the block's correspondingreference picture and then stored in accordance with the followingequations:

MV_x_stored=MV_x/(POC_picture−POC_reference)

MV_y_stored=MV_y/(POC_picture−POC_reference)

wherein, POC_picture and POC_reference denote POC of the picture and POCof reference picture for the block, and MV_x and MV_y denote the (x,y)components of motion vector for the block. The motion vector componentsof MV_x and MV_y can then be normalized as MV_x_stored and MV_y_stored.

In order to reduce rounding errors, the stored motion vector can bescaled. In some embodiments, the stored motion vector and/or the scalingfactor can be specified and included in bitstream, at the SPS, PPS orother levels. Thus, an alternative normalized motion vector is definedas follows:

-   -   Normalized        MV_x_stored=scaling_factor*MV_x/(POC_picture−POC_reference).    -   Normalized        MV_y_stored=scaling_factor*MV_y/(POC_picture−POC_reference).

where

the scaling_factor is a scaling factor specified and can be, by way ofnon-limiting example 8, 16, 24 or more.

In some embodiments, if a block has motion vector for a single list, forexample, list 0 only, motion information (motion vector, referenceindex, RPS for the current picture etc.) for list 0 only can be storedor the normalized motion vector for list 0 only can be stored. If anembodiment comprises multiple lists, (for example, if both list 0, list1are available for a block), then motion information (motion vector,reference index, RPS for the current picture etc.) for eitherlist0/list1 can be stored or the normalized motion vector forlist0/list1 can stored. Additionally, if an embodiment the blockcomprises motion vectors for a single list (for example, list 1) wherein which are multiple list options, (for example list1 only, but lists 0and 1 exist and are available), then motion information (motion vector,reference index, RPS for the current picture etc.) for list 1 only canbe stored or the normalized motion vector for list 1 only can be stored.A tabular formation 1100 of this example is presented in FIG. 11, inwhich 1102 indicates whether motion vector information is available forlist0 , 1104 indicates whether motion vector information is availablefor list1, 1106 indicates which motion information will be stored basedon the various conditions/availability of list0/list1 presented in therows of the table 1100.

However, in some alternate embodiments in which a temporal motion vectoris used, a stored temporal motion vector is accordingly scaledregardless of which lists are available for the current block.

The execution of the sequences of instructions required to practice theembodiments can be performed by a computer system 1200 as shown in FIG.12. In an embodiment, execution of the sequences of instructions isperformed by a single computer system 1200. According to otherembodiments, two or more computer systems 1200 coupled by acommunication link 1215 can perform the sequence of instructions incoordination with one another. Although a description of only onecomputer system 1200 will be presented below, however, it should beunderstood that any number of computer systems 1200 can be employed topractice the embodiments.

A computer system 1200 according to an embodiment will now be describedwith reference to FIG. 12, which is a block diagram of the functionalcomponents of a computer system 1200. As used herein, the term computersystem 1200 is broadly used to describe any computing device that canstore and independently run one or more programs.

Each computer system 1200 can include a communication interface 1214coupled to the bus 1206. The communication interface 1214 providestwo-way communication between computer systems 1200. The communicationinterface 1214 of a respective computer system 1200 transmits andreceives electrical, electromagnetic or optical signals, that includedata streams representing various types of signal information, e.g.,instructions, messages and data. A communication link 1215 links onecomputer system 1200 with another computer system 1200. For example, thecommunication link 1215 can be a LAN, in which case the communicationinterface 1214 can be a LAN card, or the communication link 1215 can bea PSTN, in which case the communication interface 1214 can be anintegrated services digital network (ISDN) card or a modem, or thecommunication link 1215 can be the Internet, in which case thecommunication interface 1214 can be a dial-up, cable or wireless modem.

A computer system 1200 can transmit and receive messages, data, andinstructions, including program, i.e., application, code, through itsrespective communication link 1215 and communication interface 1214.Received program code can be executed by the respective processor(s)1207 as it is received, and/or stored in the storage device 1210, orother associated non-volatile media, for later execution.

In an embodiment, the computer system 1200 operates in conjunction witha data storage system 1231, e.g., a data storage system 1231 thatcontains a database 1232 that is readily accessible by the computersystem 1200. The computer system 1200 communicates with the data storagesystem 1231 through a data interface 1233. A data interface 1233, whichis coupled to the bus 1206, transmits and receives electrical,electromagnetic or optical signals, that include data streamsrepresenting various types of signal information, e.g., instructions,messages and data. In embodiments, the functions of the data interface1233 can be performed by the communication interface 1214.

Computer system 1200 includes a bus 1206 or other communicationmechanism for communicating instructions, messages and data,collectively, information, and one or more processors 1207 coupled withthe bus 1206 for processing information. Computer system 1200 alsoincludes a main memory 1208, such as a random access memory (RAM) orother dynamic storage device, coupled to the bus 1206 for storingdynamic data and instructions to be executed by the processor(s) 1207.The main memory 1208 also can be used for storing temporary data, i.e.,variables, or other intermediate information during execution ofinstructions by the processor(s) 1207.

The computer system 1200 can further include a read only memory (ROM)1209 or other static storage device coupled to the bus 1206 for storingstatic data and instructions for the processor(s) 1207. A storage device1210, such as a magnetic disk or optical disk, can also be provided andcoupled to the bus 1206 for storing data and instructions for theprocessor(s) 1207.

A computer system 1200 can be coupled via the bus 1206 to a displaydevice 1211, such as, but not limited to, a cathode ray tube (CRT) or aliquid-crystal display (LCD) monitor, for displaying information to auser. An input device 1212, e.g., alphanumeric and other keys, iscoupled to the bus 1206 for communicating information and commandselections to the processor(s) 1207.

According to one embodiment, an individual computer system 1200 performsspecific operations by their respective processor(s) 1207 executing oneor more sequences of one or more instructions contained in the mainmemory 1208. Such instructions can be read into the main memory 1208from another computer-usable medium, such as the ROM 1209 or the storagedevice 1210. Execution of the sequences of instructions contained in themain memory 1208 causes the processor(s) 1207 to perform the processesdescribed herein. In alternative embodiments, hard-wired circuitry canbe used in place of or in combination with software instructions. Thus,embodiments are not limited to any specific combination of hardwarecircuitry and/or software.

The term “computer-usable medium,” as used herein, refers to any mediumthat provides information or is usable by the processor(s) 1207. Such amedium can take many forms, including, but not limited to, non-volatile,volatile and transmission media. Non-volatile media, i.e., media thatcan retain information in the absence of power, includes the ROM 1209,CD ROM, magnetic tape, and magnetic discs. Volatile media, i.e., mediathat can not retain information in the absence of power, includes themain memory 1208. Transmission media includes coaxial cables, copperwire and fiber optics, including the wires that comprise the bus 1206.Transmission media can also take the form of carrier waves; i.e.,electromagnetic waves that can be modulated, as in frequency, amplitudeor phase, to transmit information signals. Additionally, transmissionmedia can take the form of acoustic or light waves, such as thosegenerated during radio wave and infrared data communications.

In the foregoing specification, the embodiments have been described withreference to specific elements thereof. It will, however, be evidentthat various modifications and changes can be made thereto withoutdeparting from the broader spirit and scope of the embodiments. Forexample, the reader is to understand that the specific ordering andcombination of process actions shown in the process flow diagramsdescribed herein is merely illustrative, and that using different oradditional process actions, or a different combination or ordering ofprocess actions can be used to enact the embodiments. The specificationand drawings are, accordingly, to be regarded in an illustrative ratherthan restrictive sense.

It should also be noted that the present invention can be implemented ina variety of computer systems. The various techniques described hereincan be implemented in hardware or software, or a combination of both.Preferably, the techniques are implemented in computer programsexecuting on programmable computers that each include a processor, astorage medium readable by the processor (including volatile andnon-volatile memory and/or storage elements), at least one input device,and at least one output device. Program code is applied to data enteredusing the input device to perform the functions described above and togenerate output information. The output information is applied to one ormore output devices. Each program is preferably implemented in a highlevel procedural or object oriented programming language to communicatewith a computer system. However, the programs can be implemented inassembly or machine language, if desired. In any case, the language canbe a compiled or interpreted language. Each such computer program ispreferably stored on a storage medium or device (e.g., ROM or magneticdisk) that is readable by a general or special purpose programmablecomputer for configuring and operating the computer when the storagemedium or device is read by the computer to perform the proceduresdescribed above. The system can also be considered to be implemented asa computer-readable storage medium, configured with a computer program,where the storage medium so configured causes a computer to operate in aspecific and predefined manner. Further, the storage elements of theexemplary computing applications can be relational or sequential (flatfile) type computing databases that are capable of storing data invarious combinations and configurations.

FIG. 13 is a high-level view of a source device 1312 and destinationdevice 1310 that may incorporate features of the systems and devicesdescribed herein. As shown in FIG. 13, example video coding system 1310includes a source device 1312 and a destination device 1314 where, inthis example, the source device 1312 generates encoded video data.Accordingly, source device 1312 may be referred to as a video encodingdevice. Destination device 1314 may decode the encoded video datagenerated by source device 1312. Accordingly, destination device 1314may be referred to as a video decoding device. Source device 1312 anddestination device 1314 may be examples of video coding devices.

Destination device 1314 may receive encoded video data from sourcedevice 1312 via a channel 1316. Channel 1316 may comprise a type ofmedium or device capable of moving the encoded video data from sourcedevice 1312 to destination device 1314. In one example, channel 1316 maycomprise a communication medium that enables source device 1312 totransmit encoded video data directly to destination device 1314 inreal-time.

In this example, source device 1312 may modulate the encoded video dataaccording to a communication standard, such as a wireless communicationprotocol, and may transmit the modulated video data to destinationdevice 1314. The communication medium may comprise a wireless or wiredcommunication medium, such as a radio frequency (RF) spectrum or one ormore physical transmission lines. The communication medium may form partof a packet-based network, such as a local area network, a wide-areanetwork, or a global network such as the Internet. The communicationmedium may include routers, switches, base stations, or other equipmentthat facilitates communication from source device 1312 to destinationdevice 1314. In another example, channel 1316 may correspond to astorage medium that stores the encoded video data generated by sourcedevice 1312.

In the example of FIG. 13, source device 1312 includes a video source1318, video encoder 1320, and an output interface 1322. In some cases,output interface 1328 may include a modulator/demodulator (modem) and/ora transmitter. In source device 1312, video source 1318 may include asource such as a video capture device, e.g., a video camera, a videoarchive containing previously captured video data, a video feedinterface to receive video data from a video content provider, and/or acomputer graphics system for generating video data, or a combination ofsuch sources.

Video encoder 1320 may encode the captured, pre-captured, orcomputer-generated video data. An input image may be received by thevideo encoder 1320 and stored in the input frame memory 1321. Thegeneral purpose processor 1323 may load information from here andperform encoding. The program for driving the general purpose processormay be loaded from a storage device, such as the example memory modulesdepicted in FIG. 13. The general purpose processor may use processingmemory 1322 to perform the encoding, and the output of the encodinginformation by the general processor may be stored in a buffer, such asoutput buffer 1326.

The video encoder 1320 may include a resampling module 1325 which may beconfigured to code (e.g., encode) video data in a scalable video codingscheme that defines at least one base layer and at least one enhancementlayer. Resampling module 1325 may resample at least some video data aspart of an encoding process, wherein resampling may be performed in anadaptive manner using resampling filters.

The encoded video data, e.g., a coded bit stream, may be transmitteddirectly to destination device 1314 via output interface 1328 of sourcedevice 1312. In the example of FIG. 13, destination device 1314 includesan input interface 1338, a video decoder 1330, and a display device1332. In some cases, input interface 1328 may include a receiver and/ora modem. Input interface 1338 of destination device 1314 receivesencoded video data over channel 1316. The encoded video data may includea variety of syntax elements generated by video encoder 1320 thatrepresent the video data. Such syntax elements may be included with theencoded video data transmitted on a communication medium, stored on astorage medium, or stored a file server.

The encoded video data may also be stored onto a storage medium or afile server for later access by destination device 1314 for decodingand/or playback. For example, the coded bitstream may be temporarilystored in the input buffer 1331, then loaded in to the general purposeprocessor 1333. The program for driving the general purpose processormay be loaded from a storage device or memory. The general purposeprocessor may use a process memory 1332 to perform the decoding. Thevideo decoder 1330 may also include a resampling module 1335 similar tothe resampling module 1325 employed in the video encoder 1320.

FIG. 13 depicts the resampling module 1335 separately from the generalpurpose processor 1333, but it would be appreciated by one of skill inthe art that the resampling function may be performed by a programexecuted by the general purpose processor, and the processing in thevideo encoder may be accomplished using one or more processors. Thedecoded image(s) may be stored in the output frame buffer 1336 and thensent out to the input interface 1338.

Display device 1338 may be integrated with or may be external todestination device 1314. In some examples, destination device 1314 mayinclude an integrated display device and may also be configured tointerface with an external display device. In other examples,destination device 1314 may be a display device. In general, displaydevice 1338 displays the decoded video data to a user.

Video encoder 1320 and video decoder 1330 may operate according to avideo compression standard. ITU-T VCEG (Q6/16) and ISO/IEC MPEG (JTC1/SC 29/WG 11) are studying the potential need for standardization offuture video coding technology with a compression capability thatsignificantly exceeds that of the current High Efficiency Video CodingHEVC standard (including its current extensions and near-term extensionsfor screen content coding and high-dynamic-range coding). The groups areworking together on this exploration activity in a joint collaborationeffort known as the Joint Video Exploration Team (WET) to evaluatecompression technology designs proposed by their experts in this area. Arecent capture of JVET development is described in the “AlgorithmDescription of Joint Exploration Test Model 5 (JEM 5)”, WET-E1001-V2,authored by J. Chen, E. Alshina, G. Sullivan, J. Ohm, J. Boyce.

Additionally or alternatively, video encoder 1320 and video decoder 1330may operate according to other proprietary or industry standards thatfunction with the disclosed JVET features. Thus, other standards such asthe ITU-T H.264 standard, alternatively referred to as MPEG-4, Part 10,Advanced Video Coding (AVC), or extensions of such standards. Thus,while newly developed for JVET, techniques of this disclosure are notlimited to any particular coding standard or technique. Other examplesof video compression standards and techniques include MPEG-2, ITU-TH.263 and proprietary or open source compression formats and relatedformats.

Video encoder 1320 and video decoder 1330 may be implemented inhardware, software, firmware or any combination thereof. For example,the video encoder 1320 and decoder 1330 may employ one or moreprocessors, digital signal processors (DSPs), application specificintegrated circuits (ASICs), field programmable gate arrays (FPGAs),discrete logic, or any combinations thereof. When the video encoder 1320and decoder 1330 are implemented partially in software, a device maystore instructions for the software in a suitable, non-transitorycomputer-readable storage medium and may execute the instructions inhardware using one or more processors to perform the techniques of thisdisclosure. Each of video encoder 1320 and video decoder 1330 may beincluded in one or more encoders or decoders, either of which may beintegrated as part of a combined encoder/decoder (CODEC) in a respectivedevice.

Aspects of the subject matter described herein may be described in thegeneral context of computer-executable instructions, such as programmodules, being executed by a computer, such as the general-purposeprocessors 1323 and 1333 described above. Generally, program modulesinclude routines, programs, objects, components, data structures, and soforth, which perform particular tasks or implement particular abstractdata types. Aspects of the subject matter described herein may also bepracticed in distributed computing environments where tasks areperformed by remote processing devices that are linked through acommunications network. In a distributed computing environment, programmodules may be located in both local and remote computer storage mediaincluding memory storage devices.

Examples of memory include random access memory (RAM), read only memory(ROM), or both. Memory may store instructions, such as source code orbinary code, for performing the techniques described above. Memory mayalso be used for storing variables or other intermediate informationduring execution of instructions to be executed by a processor, such asprocessor 1323 and 1333.

A storage device may also store instructions, instructions, such assource code or binary code, for performing the techniques describedabove. A storage device may additionally store data used and manipulatedby the computer processor. For example, a storage device in a videoencoder 1320 or a video decoder 1330 may be a database that is accessedby computer system 1323 or 1333. Other examples of storage deviceinclude random access memory (RAM), read only memory (ROM), a harddrive, a magnetic disk, an optical disk, a CD-ROM, a DVD, a flashmemory, a USB memory card, or any other medium from which a computer canread.

A memory or storage device may be an example of a non-transitorycomputer-readable storage medium for use by or in connection with thevideo encoder and/or decoder. The non-transitory computer-readablestorage medium contains instructions for controlling a computer systemto be configured to perform functions described by particularembodiments. The instructions, when executed by one or more computerprocessors, may be configured to perform that which is described inparticular embodiments.

Also, it is noted that some embodiments have been described as a processwhich can be depicted as a flow diagram or block diagram. Although eachmay describe the operations as a sequential process, many of theoperations can be performed in parallel or concurrently. In addition,the order of the operations may be rearranged. A process may haveadditional steps not included in the figures.

Particular embodiments may be implemented in a non-transitorycomputer-readable storage medium for use by or in connection with theinstruction execution system, apparatus, system, or machine. Thecomputer-readable storage medium contains instructions for controlling acomputer system to perform a method described by particular embodiments.The computer system may include one or more computing devices. Theinstructions, when executed by one or more computer processors, may beconfigured to perform that which is described in particular embodiments

As used in the description herein and throughout the claims that follow,“a”, “an”, and “the” includes plural references unless the contextclearly dictates otherwise. Also, as used in the description herein andthroughout the claims that follow, the meaning of “in” includes “in” and“on” unless the context clearly dictates otherwise.

Although exemplary embodiments of the invention have been described indetail and in language specific to structural features and/ormethodological acts above, it is to be understood that those skilled inthe art will readily appreciate that many additional modifications arepossible in the exemplary embodiments without materially departing fromthe novel teachings and advantages of the invention. Moreover, it is tobe understood that the subject matter defined in the appended claims isnot necessarily limited to the specific features or acts describedabove. Accordingly, these and all such modifications are intended to beincluded within the scope of this invention construed in breadth andscope in accordance with the appended claims.

What is claimed is:
 1. A method of inter-coding comprising: determining motion information associated with a collocated picture set; determining motion information associated with a current coding unit; updating said motion information associated with said collocated picture set with motion information associated with said current coding unit, if it is determined that said motion information associated with said collocated picture set is to be updated with said motion information associated with said current coding unit; and encoding said current coding unit; wherein said encoded current coding unit includes an indicator identifying whether said motion information associated with said current coding unit is used to update said motion information associated with said collocated picture set.
 2. The method of inter-coding of claim 1 wherein a plurality of collocated picture sets are available and one of said plurality of collocated picture sets is updated.
 3. The method of inter-coding of claim 1 wherein said indicator is included in a NAL unit associated with said current coding unit.
 4. The method of inter-coding of claim 3 wherein said indicator is included within a header of said NAL unit.
 5. The method of inter-coding of claim 4 wherein said indicator is a single bit.
 6. The method of inter-coding of claim 5 wherein said current coding unit is encoded according to HEVC.
 7. The method of inter-coding of claim 5 wherein said current coding using is encoded according to VVC.
 8. The method of inter-coding of claim 5 wherein said current coding using is encoded according to JVET.
 9. The method of inter-coding of claim 1 further comprising: receiving said encoded current coding unit; determining whether said encoded current coding unit includes said indicator; and storing said motion information associated with said current coding unit as part of said collocated picture set, if said indicator is determined to be present.
 10. The method of inter-coding of claim 9 wherein said indicator is included in a NAL unit associated with said current coding unit.
 11. The method of inter-coding of claim 10 wherein said indicator is included within a header of said NAL unit.
 12. The method of inter-coding of claim 11 wherein said indicator is a single bit.
 13. The method of inter-coding of claim 12 wherein said current coding unit is decoded according to HEVC.
 14. The method of inter-coding of claim 12 wherein said current coding using is decoded according to VVC.
 15. The method of inter-coding of claim 12 wherein said current coding using is decoded according to JVET.
 16. A system of inter-coding comprising: storing in an encoder memory motion information associated with a collocated picture set; storing in said encoder memory motion information associated with a current coding unit; updating said encoder memory with motion information associated with said collocated picture set with motion information associated with said current coding unit, if it is determined that said motion information associated with said collocated picture set is to be updated with said motion information associated with said current coding unit; and encoding said current coding unit; wherein said encoded current coding unit includes an indicator identifying whether said motion information associated with said current coding unit is used to update said motion information associated with said collocated picture set.
 17. The system of inter-coding of claim 16 further comprising: storing in a decoder memory said encoded current coding unit; determining whether said encoded current coding unit includes said indicator; and storing in a decoder memory said motion information associated with said current coding unit as part of said collocated picture set, if said indicator is determined to be present.
 18. The system of inter-coding of claim 17 wherein said indicator is included in a NAL unit associated with said current coding unit.
 19. The method of inter-coding of claim 18 wherein said indicator is included within a header of said NAL unit.
 20. The method of inter-coding of claim 19 wherein said current coding unit is encoded according to at least one of HEVC, VVC and JVET. 